Pesticides, depending on the characteristics of the active substance that they contain and on their use, may be formulated as dry powders, wettable powders, dispersible granules, concentrated suspensions, concentrated emulsions and solutions, and their application on the soil, seeds and plants foliage generally occurs in the form of aqueous solution, suspension or emulsion.
In case the active substance is solid and insoluble in water, in order to disperse and suspend it in water, surfactants, that can be polymeric or non-polymeric, are normally employed; beside assisting the formation of mixtures of water and water insoluble materials, the surfactants reduce the interfacial tension between water and the treated substrate and improve the distribution and penetration of the active substance. They are generally said to act as dispersants, wetting agents and penetration enhancers.
Wetting/dispersing agents that are commonly used in the preparation of agrochemical compositions containing solid active ingredients which are insoluble in water are, for instance, sodium lignosulfonates, sodium naphthalene sulfonate/formaldehyde condensates, tristyrylphenolethoxylate phosphate esters, ethylene oxide/propylene oxide block copolymers.
A variety of polyacrylic polymeric surfactants is known to act as dispersants, milling and wetting agents for agrochemical compositions; in polyacrylic polymeric surfactants, one portion of the structure is typically made hydrophilic by inserting polyethoxylated segments, carboxylic acid groups, sulfonic acid groups, while the hydrophobic portion of the structure typically contains fatty alkyl chains, aryl groups, polypropoxylated segments.
Among the polyacrylic polymeric surfactants, particularly those that are obtained by copolymerisation of monomers containing strongly acidic groups such as sulfonic groups, are known and have been appreciated since a long time.
US 2006/0142159 describes the use of polymers obtained by radical polymerisation of 2-acrylamido-2-methylpropanesulfonic acid and/or salt thereof with one or more hydrophobic macromonomers, as stabilisers for concentrated suspensions.
WO 2008/015185 discloses pesticidal agrochemical compositions, characterised by the fact that they comprise from 0.5 to 10% by weight of a polymer obtained by polymerising: a) from 60 to 90% molar of acrylic or methacrylic acid and/or 2-acrylamido-2-methylpropanesulfonic acid; b) from 10 to 40% molar of an acrylic or methacrylic acid ester of a C8-C18 alcohol.
WO 2010/121976 relates to agrochemical formulations comprising an agrochemical active and a dispersant which is a copolymer of olefinically unsaturated carboxylic acids and its salts, olefinically unsaturated monomers bearing a hydrophobic moiety and, optionally, olefinically unsaturated sulfonic acid or phosphonic acids monomers and its salts; examples are given for the use of benzylmethacrylate, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid copolymers.
More examples of polyacrylic polymeric dispersants for agrochemical compositions are given in U.S. Pat. No. 6,767,865 (styrene/(meth)acrylic acid copolymers) and in U.S. Pat. No. 5,139,773 (methyl methacrylate/methacrylic acid/methoxy (polyethyleneglycol) methacrylate copolymers).
Similar polyacrylic polymeric dispersants are also known to disperse inorganic materials in water.
U.S. Pat. No. 6,093,764 relates to polymeric dispersants based on at least one monomer which is ethylenically unsaturated and has a carboxylic function and at least one surface-active oxyalkylated monomer which is ethylenically unsaturated and terminates with a hydrophobic chain; the dispersants are prepared by radical copolymerization of the monomers. The dispersants of U.S. Pat. No. 6,093,764 are useful for dispersing in water mineral substances, such as calcium carbonates, calcium sulphate, titanium dioxide, talc, mica and other minerals.
U.S. Pat. No. 5,320,672 describes associative dispersants for pigments, particularly for dispersing kaolin clay in a paper coating composition, that are the sodium salt of acrylic acid copolymerized with an acrylate ester containing 20 moles of ethylene oxide and phenyl stearyl hydrophobes.
It has now been found that the use, as dispersing and wetting agent, of a carboxylated water soluble polymer based on one or more ethylenically unsaturated carboxylic acids, from 5% to 55% of the carboxylic groups of said water soluble polymer being esterified with a polyalkoxylated polystyrylphenol, provides unexpected advantages in the preparation of agrochemical compositions comprising at least a water insoluble solid organic pesticide.
The water soluble carboxylated polymer (“water soluble polymer”) may be prepared in two steps by i) radically polymerizing the ethylenically unsaturated mono carboxylic acids, bi-carboxylic acids or anhydride thereof, and ii) esterifying in a subsequent step the thus obtained carboxylated polymer with specific amounts of the polyalkoxylated polystyrylphenol.
The water soluble carboxylated polymer according to the invention behaves as a very good dispersing agent in grinding water insoluble organic agrochemically active substances which are to be dispersed in water; furthermore, the polymer is very efficient in promoting the formation of stable concentrated aqueous systems comprising the water insoluble organic agrochemically active substances and it helps their final dilution in water.
Therefore, the aqueous agrochemical composition of the invention is advantageously a suspension concentrate (SC) in which the water insoluble organic agrochemically active substance is suspended in water at concentration from about 50 to about 1100 g/I.
Suspension concentrates are stable liquid suspensions of very small pesticide particles that offer many advantages, such as ease of handling and dosing, safety to the operator and the environment, and economy.
Because of the hydrophobicity and low density of most of the water insoluble organic agrochemically active substances, the preparation of their stable suspension concentrate is often a challenging objective and requires the accurate tailoring of the wetting and dispersing agents. Most often, combination of different substances, each performing a specific function (as milling agent, thinner, wetting agent, dispersant) are required.
It is therefore highly desirable in the field to provide a versatile unique chemical that is able to perform all the above functions in the preparation of stable suspension concentrates of different insoluble organic agrochemically active substances, even in admixture.